Krupa is a typical karstic river that flows into Zrmanja after 10 km of its own flow and it is its biggest tributary. The most beautiful part of Krupa is rich in lavish waterfalls and tufa cascades. More precisely, there are nine of them which end in a high waterfall. Kudin bridge takes you over the waterfall itself. The bridge has been declared as a Cultural monument due to the fact that it is the oldest crossing over Krupa. The entire area of Krupa river has been protected as a Cultural landscape.